1. Field of the Invention
The present invention relates to an optical pickup apparatus which is used for recording and/or reproducing data on a light-using recording medium such as a digital versatile disk and a compact disk, and to an electronic equipment having the optical pickup apparatus.
2. Description of the Related Art
In recent years, a notebook-sized personal computer (laptop for short) excelling in mobile convenience has been pervaded, and along with the pervasion of the laptop, there is a tendency of reduction in size and weight of an information recording/reproducing apparatus which serves as an apparatus for recording/reproducing data on a recording medium used in the laptop. Further, a widely-used information recording/reproducing apparatus reduced in size and weight is capable of recording/reproducing data on a plurality of recording mediums such as a digital versatile disk (DVD for short) and a compact disk (CD for short). Such an apparatus is provided with a plurality of laser light sources for recording (writing) and reproducing (reading) data respectively on the plurality of recording mediums, and provided with a laser driver as an integrated circuit (IC) for controlling a light emitting operation of the laser light sources.
FIG. 8 is a schematic view showing an optical layout of a configuration of an optical pickup apparatus 1 according to a related art. FIG. 8 illustrates the conventional optical pickup apparatus 1 of typical type having two pieces of laser light sources 2, 3 and a laser driver 8.
The optical pickup apparatus 1 generally includes: two pieces of integrated light-receiving and -emitting elements 2, 3, each of which has a member collectively composed of a light source for emitting laser light and a light receiving portion for receiving light reflected by a recording medium; a beam splitter 4 as an optical branching element; a collimation lens 5; an erecting mirror 6; an objective lens 7; and a laser driver 8 for controlling an light emitting operation of a semiconductor laser as a light source.
Laser light is emitted from the semiconductor laser as a light source of the integrated light-receiving and -emitting element 2 or the integrated light-receiving and -emitting element 3. The laser light is reflected or transmitted by the beam splitter 4 where the laser light is formed into parallel light, and then reflected by the erecting mirror 6 to be thereby guided to the objective lens 7. The parallel light is formed into converging light by passing through the objective lens 7, and the converging light is converged on one point on a disc (which may be noted as “disk”) 9 as a recording medium. The converging light is reflected by the disc 9, and travels back by passing through the objective lens 7 again where the light is formed into parallel light, and being reflected by the erecting mirror 6 to thereby pass through the collimation lens 5 and then reflected or transmitted by the beam splitter 4. The light thus goes back to the integrated light-receiving and -emitting element 2 or the integrated light-receiving and -emitting element 3 by tracking back a route reversely that the light had traveled.
The light (which may be referred to as return light) reflected by the disk 9 is split by a hologram element disposed on a surface of the integrated light-receiving and -emitting element 2 or integrated light-receiving and -emitting element 3, and then enters the light receiving portion. The light receiving portion is provided with a light receiving element which obtains a light signal from the light received. The light signal is converted into an electronic signal which is used for recording, reproducing, and deleting data, or used as a servo signal.
The optical pickup apparatus 1 as described above is reduced in size more rapidly so as to be built in the laptop. Thus, the light-receiving and -emitting elements 2, 3, each of which is provided with a semiconductor laser for dealing with both media of CD and DVD to heighten an added value, or heat-generating components such as the laser driver 8 are concentrated in a thin package of small size in the optical pickup apparatus 1.
FIG. 9 is a plan view schematically showing the configuration of the optical pickup apparatus 1 shown in FIG. 8. In an actuator 11 are mounted two pieces of the integrated light-receiving and -emitting elements 2, 3, the laser driver 8, the beam splitter, 4, the collimation lens 5, the erecting mirror 6, and the objective lens 7. The actuator 11 is installed in a housing 12 which is a metallic frame member. The actuator 11 has a magnetic member, a coil, or the like member, and serves as driving means which utilizes electromagnetic force. The actuator 11 drives the objective lens 7 mounted therein, for tracking that the objective lens 7 is made to follow a track in a recording medium, and for focusing that a light converging position on an information recording surface is adjusted.
The integrated light-receiving and -emitting elements 2, 3 and the laser driver 8 are mounted in a flexible resin board 13 (FPC for short) which is a print wiring board. Further, the optical pickup apparatus 1 has a structure that the laser driver 8 is disposed between two pieces of the integrated light-receiving and -emitting elements 2, 3 so as to decrease an installation area thereof so that the apparatus can be downsized.
As the information technology develops, a double speed recording onto a recording medium develops to a higher level. Under such a circumstance, there is a tendency that an output of the semiconductor laser serving as a laser light source used for recording/reproducing data on a recording medium i.e., the disc 9 becomes higher and moreover, there is another tendency that an output of the laser driver 8 for driving the semiconductor laser also becomes higher, resulting in a higher power consumption. Such a higher output of the semiconductor and an increase in the power consumption of the laser driver 8 lead an increase in heat generated by the optical pickup apparatus having the semiconductor laser and the laser driver, so that the information recording/reproducing apparatus will suffer from a very intensive heat environment. Since the semiconductor laser is a component which is weak against heat even though it is a heat generating source, there is a problem such that a temperature rise of the semiconductor laser causes a decrease in a luminous efficiency.
In order to cope with the problem described above, there is a conventionally proposed technique of forming a concavo-convex-shaped radiator part on a surface portion of a housing which faces a recording medium (refer to Japanese Unexamined Patent Publication JP-A 2004-152408). In JP-A 2004-152408, by virtue of the radiator part formed on the housing, the heat generated especially by the light source can be released to outside of the optical pickup apparatus by means of a rotating recoding medium and the concavo-convex-shaped radiator part in cooperation with each other, so that the heat is prevented from stagnating in the apparatus, allowing stabilization on operation of the apparatus.
However, there resides the following problem in the technique of JP-A 2004-152408 which is focused on the release of heat generated especially by the light source to outside of the apparatus by means of the radiator part and the rotating recording medium. The optical pickup apparatus is provided with the laser driver which is an integrated circuit for driving and controlling the light source generating a larger amount of heat than the semiconductor laser, and therefore the action effected by the radiator part and rotating recording medium is not sufficient at all to release the heat generated by the laser driver and semiconductor laser which have higher power consumption or higher output.
There is another conventional technique which proposes to focus on a layout of the laser driver and semiconductor laser so that the laser driver is disposed in a downstream side in a rotational direction of the recording medium from two pieces of the semiconductor lasers, and which proposes to form separate housings for installing the laser driver and for installing the semiconductor laser (refer to Japanese Unexamined Patent Publication JP-A 2005-196923). In JP-A 2005-196923, the heat generated by the laser driver is not brought to the semiconductor laser by air flow created by rotation of the recording medium and moreover, the housing for installing the laser driver and the housing for installing the semiconductor laser are separate from each other, with the result that the heat generated by the laser driver is not conducted to the housing for installing the semiconductor laser and therefore, the semiconductor laser can be prevented from being excessively heated so that the semiconductor laser can continue to operate stably.
However, in the technique of JP-A 2005-196923, there is a constraint that the laser driver has to be disposed indispensably in the downstream side in the rotational direction of the recording medium from two pieces of the semiconductor lasers. Due to the constraint, a planar installation space is large, with the result that the apparatus has a limit in miniaturization thereof.